The present invention relates to cable trays and in particular to ladder-type cable trays with interlocking design of modular units for many cabling applications.
Cable ladders are commonly used in many wire and cabling applications, for example, in power distribution systems, communications centers, data processing and industrial installations to support the extensive cabling systems necessary in these applications. Ladder-type construction is open to all sides and allows easy access to cables which frequently have to be checked or rerouted.
Current cable ladders are constructed of heavy steel bolted or fastened together into extended runs. Components are often large and bulky. Construction of the system or chances in the construction requires considerable effort to use fasteners to connect each rung to the side-rails.
U.S. Pat. No. 5,465,929 to Dooley and U.S. Pat. No. 5,580,014 to Rinderer both disclose ladder-type cable tray systems which require fasteners. U.S. Pat. No. 4,319,724 to Bradbury discloses a ladder-type cable tray with rungs which are disposed in slots on the side-rails for a friction fit In this construction, the rungs must be placed in the side-rails during assembly and may not be removed from the side-rail without dissassembling the side-rail, which requires detaching it from the support surface This makes modification difficult In addition, the design of the Bradbury patent requires the user to cut side-rails and rungs to the desired length and does not provide a modular construction adaptable to different uses.
Thus it would be desirable to provide a ladder-type cable tray which would be lightweight, simple to construct, without requiring fasteners, and easy to transport and store.
Accordingly, it is a principal object of the present invention to overcome disadvantages associated with prior art and provide an interlocking, modular ladder-type cable tray which is quickly assembled and simple to install and uninstall and does not require fasteners for the rungs. Its modular construction allows for the use of smaller components, offering the advantages of ease in transport and storage, and the ability to make changes in layout as necessary.
In accordance with a preferred embodiment of the present invention, there is thus provided a ladder-type cable tray for cables or the like, the ladder including:
one or more pairs of L-shaped side-rail members having vertical and horizontal sides, the vertical side having formed therein a protruding spring tab disposed above a socket;
one or more U-shaped rung members formed at either end with a flange enclosing a U-shaped opening and defining a folded edge terminating in at least one tooth, the folded edge having formed therein a slot for engaging the spring tab;
such that upon insertion of the rung member tooth into the socket on the side-rail, the spring tab is deflected laterally and returns to its position to engage the locking slot in the rung and lock the rung to the side-rail, the locked rung forming a support platform for the cables in a rigid fashion.
In a preferred embodiment of the invention, a ladder-type cable tray is provided including two generally parallel L-shaped side-rails interlocked with one or more cross-pieces forming a ladder rung. The rungs interlock in a non-rotational manner so as to provide stability to the ladder.
The side-rail is formed with a spring tab, a C-shaped socket and two or more apertures. The rung is provided on each end with a locking slot for engaging the spring tab, and is provided with two or more teeth, two or more pins and a notch. The ladder-type cable tray is assembled by inserting the teeth of the rung into the C-shaped sockets on a pair of oppositely-facing side-rails and depressing the rung, so that the spring tab is deflected laterally and returns to its position, becoming engaged in the locking slot formed in the rung. The teeth prevent rotation and slippage of the rung. As the rung is depressed the pins on the rung are inserted into the apertures formed on the side-rail. When the rung abuts the side-rail, a notch formed on the outer edge of the rung allows the pins to be fully inserted into the apertures formed on the side-rail, so that the rung becomes seated securely on the side-rail as the notch edge abuts the side-rail edge. In this interlocked engagement, the insertion of the teeth in the C-shaped socket and the insertion of the pins in the apertures cause the notch edge to abut the side-rail edge and form a rigid construction which prevents relative rotation or movement between the rung and the side-rail.
The ladder can be mounted in a vertical or horizontal fashion, and in areas with limited accessibility. Side-rails can be constructed with bends of any angle for construction of systems which bend and turn. Rungs can be mounted in any order along the side-rails during assembly and installation. For disassembly purposes, the spring tab is depressed so as to disengage the spring tab from the locking slot enabling clearance for removal of the rung from its position in the ladder-type cable tray. The lack of tools needed to do this and the ease with which disassembly can be accomplished allows the user the ability to make adjustments to the cable tray as needed with a minimum of effort
One or more of the side-rails is attached to a wall by means of mounting holes provided on the side-rail Additional mounting holes may be provided for optional mounting alternatives.
In a preferred embodiment, the side-rails are mounted in a staggered fashion such that the junctions between the side-rails are not opposite one another. This provides greater strength to the cable tray construction.
Other features and advantages of the invention will become apparent from the following drawings and description.